Device and method for automatically detecting installed lamp type

Abstract

An apparatus ( 1100, 2000, 3000 ) executes an algorithm ( 2000 ) to determine a type of lamp ( 10 ) that is installed in a lighting unit ( 1000 ). The apparatus supplies power to the installed lamp ( 10 ) according to a first power control setting that will not overdrive the installed lamp when the installed lamp is of a first lamp type, and that will overdrive the installed lamp when the installed lamp is of a second lamp type. The apparatus ( 1100, 2000, 3000 ) detects whether the installed lamp ( 10 ) is overdriven at the first power control setting, and uses the detection result to determine the lamp type of the installed lamp ( 10 ). The apparatus ( 1100, 2000, 3000 ) then supplies power to the installed lamp ( 10 ) according to the determined lamp type.

1 . A device for supplying power to an installed fluorescent lamp, the device comprising:
 a first circuit for receiving an input voltage (V IN ) and in response thereto supplying power to the installed fluorescent lamp, the first circuit including:   a half bridge having first and second switches that are selectively turned on and off periodically, wherein each switch has a time T ON  in each period where the switch is turned on, and wherein the power level supplied to the installed fluorescent lamp varies with T ON , and   a resonant circuit for supplying the power from the half bridge to the installed fluorescent lamp;   a feedback signal generator for supplying a feedback signal indicating an average current passing through the half bridge;   a controller for receiving the feedback signal and in response thereto adjusting T ON ; and   a memory device for storing a starting lamp type,   wherein the controller executes a lamp type determination procedure for the installed fluorescent lamp, comprising:   retrieving from the memory device data indicating the starting lamp type;   supplying first and second control signals according to the starting lamp type to the first and second switches to cause the first circuit to warm-up the installed fluorescent lamp during a warm-up period;   after the warm-up period, during a test interval supplying the first and second control signals to the first and second switches to cause the first circuit to supply power to the installed fluorescent lamp to attempt to overdrive the installed fluorescent lamp;   monitoring T ON  during the test interval;   determining the lamp type of the installed fluorescent lamp based on the monitored T ON ; and   saving in the memory device data indicating the determined lamp type of the installed fluorescent lamp as the starting lamp type.   
     
     
         2 . The device of  claim 1 , wherein the installed fluorescent lamp has one of a first lamp type corresponding to a first, higher, power level, and a second lamp type corresponding to a second, lower, power level, and wherein the controller sets a maximum value T ON-MAX  for T ON  during the test interval corresponding to the first lamp type, and compares the monitored T ON  to T ON-MAX . 
     
     
         3 . The device of  claim 2 , wherein the controller determines whether the installed fluorescent lamp belongs to the first lamp type or belongs to the second lamp type depending on whether the monitored T ON  equals T ON-MAX  during the test interval. 
     
     
         4 . The device of  claim 2 , wherein the controller sets a threshold percentage, and determines whether the installed fluorescent lamp belongs to the first lamp type or belongs to the second lamp type depending on whether the monitored T ON  equals T ON-MAX  for at least the threshold percentage of time during the test interval. 
     
     
         5 . The device of  claim 2 , wherein the feedback signal has a value, and wherein the controller compares the feedback signal value to a target value and in response thereto adjusts T ON  to attempt to cause the feedback signal value to equal the target value. 
     
     
         6 . The device of  claim 5 , wherein the target value is selected according to one of the first and second lamp types. 
     
     
         7 . The device of  claim 6 , wherein the controller includes a comparator or amplifier that compares the feedback signal value to the target value, and wherein the controller determines that T ON  equals T ON-MAX  when an output of the comparator or amplifier is at one of its maximum and minimum values. 
     
     
         8 . The device of  claim 6 , wherein the controller includes a processor that measures T ON . 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . A method, comprising:
 supplying power to an installed lamp according to a first power control setting that will not overdrive the installed lamp when the installed lamp is of a first lamp type, and that will overdrive the installed lamp when the installed lamp is of a second lamp type and includes selectively turning on and off first and second switches of a half bridge periodically, wherein each switch has a time T ON  in each period where the switch is turned on, and wherein a power level supplied to the installed lamp varies with T ON ;   detecting whether the installed lamp is overdriven at the first power control setting;   determining the lamp type of the installed lamp based at least in part on whether the installed lamp is overdriven at the first power control setting; and   supplying the power to the installed lamp according to the determined lamp type,   wherein the first lamp type corresponds to a first, lower, power level, and the second lamp type corresponds to a second, higher, power level, and the method comprises, during a test interval;   setting a maximum value T ON-MAX  for T ON  corresponding to the first lamp type,   monitoring T ON , and   comparing the monitored T ON  to T ON-MAX ;   
     
     
         16 . The method of  claim 15 , further comprising comparing a feedback signal to a target value for driving the installed lamp, and determining whether the installed lamp is overdriven based on a result of the comparison. 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 15 , further comprising determining whether the installed lamp belongs to the first lamp type or belongs to the second lamp type depending on whether the monitored T ON  equals T ON-MAX  during the test interval. 
     
     
         20 . The method of  claim 15 , further comprising:
 supplying the power to the installed lamp according to a second power control setting that will not overdrive the installed lamp when the installed lamp is of the second lamp type, and that will overdrive the installed lamp when the installed lamp is of a third lamp type;   detecting whether the installed lamp is overdriven at the second power control setting; and   determining the lamp type of the installed lamp based at least in part on whether the installed lamp is overdriven at the second power control setting.   
     
     
         21 . The method of  claim 15 , wherein the first lamp type corresponds to a first, higher, power level lamp, and the second lamp type corresponds to a second, lower, power level lamp. 
     
     
         22 . The method of  claim 15 , further comprising saving in a memory device data indicating the determined lamp type of the installed lamp.